The whole of the links of this chain are perceptible only when the fever comes on in a _gradual_ manner. But I wish the reader to remember, that the same remote cause is often debilitating, stimulating, and depressing, and that, in certain fevers, the remote cause sometimes excites convulsions in the blood-vessels without being preceded by preternatural debility and excitability, and with but little or no depression of the system. This has often been observed in persons who have been suddenly exposed to those marsh and human miasmata which produce malignant fevers. It sometimes takes place likewise in fevers induced by local injuries. The blood-vessels in these cases are, as it were, taken by storm, instead of regular approaches. I might digress here, and show that all diseases, whether they be seated in the arteries, muscles, nerves, brain, or alimentary canal, are all preceded by debility; and that their essence consists in irregular action, or in the absence of the natural order of motion, produced or invited by predisposing debility. I might further show, that all the moral, as well as physical evil of the world consists in predisposing weakness, and in subsequent derangement of action or motion; but these collateral subjects are foreign to our present inquiry. Let us now proceed to examine how far the theory which has been delivered accords with the phenomena of fever. I shall divide these phenomena into two kinds. I. Such as are transient, and more or less common to all fevers. These I shall call _symptoms_ of fever. II. Such as, being more permanent and fixed, have given rise to certain specific names. These I shall call _states_ of fever. I shall endeavour to explain and describe each of them in the order in which they have been mentioned. I. Lassitude is the effect of the depression of the whole system, which precedes fever.